This module implements the interface to NIST’s secure hash algorithm, known as
SHA-1. SHA-1 is an improved version of the original SHA hash algorithm. It is
used in the same way as the md5 module: use new() to create an sha
object, then feed this object with arbitrary strings using the update()
method, and at any point you can ask it for the digest of the
concatenation of the strings fed to it so far. SHA-1 digests are 160 bits
instead of MD5’s 128 bits.